Heat sensitive recording material containing decolorizing agent

ABSTRACT

In a heat sensitive recording material comprising a support having a heat sensitive layer or layers thereon which comprise colorless or palely colored chromogenic substance and phenolic substance capable, upon heating, of causing color formation of said chromogenic substance, at least one organic amine derivatives are contained as a decolorizing agent in said heat sensitive layer or another layer adjacent to said heat sensitive layer. Using this recording material, two colors which are clearly distinguishable can be obtained.

United States Patent [1 1 Kohmura et al.

[451 Oct. 28, 1975 HEAT SENSITIVE RECORDING MATERIAL CONTAINING DECOLORIZING AGENT [73] Assignee: Mitsubishi Paper Mills, Ltd., Japan [22] Filed: Nov. 6, 1973 [2]] Appl. No.: 413,387

[30] Foreign Application Priority Data Nov. 8, 1972 Japan 47-111206 June 20, 1973 Japan 48-68805 [52] US. Cl. 428/411; 427/145; 427/148 [51] Int. Cl. B41M 5/18 [58] Field of Search 117/368, 36.2, 36.9

[56] References Cited UNITED STATES PATENTS 3,473,945 10/1969 Futaki 117/368 3,746,675 7/1973 Blose et a1. 117/362 X Primary Examiner-Thomas J. Herbert, Jr. Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT In a heat sensitive recording material comprising a support having a heat sensitive layer or layers thereon which comprise colorless or palely colored chromogenic substance and phenolic substance capable, upon heating, of causing color formation of said chromogenic substance, at least one organic amine derivatives are contained as a decolorizing agent in said heat sensitive layer or another layer adjacent to said heat sensitive layer. Using this recording material, two colors which are clearly distinguishable can be obtained.

10 Claims, No Drawings HEAT SENSI'IIVE RECORDING MATERIAL CONTAINING DECOLORIZING AGENT The present invention relates to a heat sensitive recording material. More particularly, it relates to a heat ,sensitive recording material characterized in that as a decolorizing agent an organic amine derivative is contained in a heat sensitive layer comprising a normally colorless or palely colored chromogenic substance and a phenolic substance capable of causing coloration of said chromogenic substance upon heating or a layer adjacent to said heat sensitive layer.

Hitherto, heat sensitive recording materials comprising the combination of a chromogenic substance such as Crystal Violet lactone and a phenolic substance such as 4,4-isopropylidene diphenol is mentioned in, for example, Japanese Patent Publication No. 14039/70.

At present, the heat sensitive recording materials are used as recording papers for printing by thermal printer such as desk-top electronic calculator or telefax, or

printing by thermal pen invarious industrial recorders. However, such recording materials as capable of forming distinguishable two or three colors on the same sheet have further been demanded. According to such method, two or three heat sensitive layers which have different color forming temperatures and simulta neously form different colors are coated on a sheet and thus mono color is formed by heating at a lower temperature and a blended color is formed by heating at a higher temperature. However, thus obtained mono color and blended color cannot be clearly distinguished from each other, and this method is not preferred for practical purpose.

The object of the present invention is to provide a multi color forming heat sensitive recording material which comprises'heat sensitive layer or layers which have different color forming temperatures and are coated on one sheet, according to which mono colors can be formed by both high temperature printing and low temperature printing by changing the printing temperature and clearly distinguishable colors can'be' formed.

In order to accomplish said object, the inventors have made researches inan attemptto attain clearly distinguishable colors by employing combination of only mono colors instead of the combination of mono color and blended color. As the result, it has been found that when an organic amine derivative is contained in a heat sensitive component-containing layer or an adjacent layer, color is formed at a temperature within a certain range, but is not formed at a temperature higher than said range.

That is, when a heat sensitive layer containing an organic amine derivative and another heat sensitive layer which contains no amine derivative and forms color different from the color formed in said heat sensitive layer containing the organic amine derivative at a higher temperature than the temperature at which said amine-containing layer forms color are coated, at a low temperature the organic amine derivative-containing layer firstly forms color and at a higher temperature said organic amine derivative-containing layer is decolorized and only said layer which forms color at the higher temperature forms color. Thus, it has become possible to obtain mono colors different in hue from each other at both high and low temperatures.

In the above case, the amine derivative is contained in one of the two heat sensitive layers. However, a heat sensitive recording material having only one heat sensitive layer which contains'chromogenic substance, phenolic substance and the amine derivative is also possible, but in this case it is necessary that the heat sensitive layer contains two kinds of the chromogenic substances and the phenolic substances, respectively.

Furthermore, when the organic amine derivative and a chromogenic substance which forms a color with said organic amine derivative are coated as an under layer and a heat sensitive layer comprising a chromogenic substance and a phenolic substance is coated thereon as an upper layer, the upper heat sensitive layer forms color at a low temperature and this upper heat sensitive layer is decolorized and the under layer forms color at a high temperature. Thus, mono colors can be obtained in both of the two layers.

In case of adding the organic amine derivative to the heat sensitive layer containing the chromogenic substance and the phenolic substance in the present invention, it is naturally required that the melting point of the organic amine derivative is higher than that of the phenolic substance, namely, the color forming temperature. Especially, the melting point of the organic amine derivative is preferably 10C 50C higher than that of the phenolic substance. Moreover, it is necessary that the organic amine derivative is insoluble in the solvent in which the chromogenic substance and the phenolic substance are dispersed. However, when the organic amine derivative is coated as a separate under layer and a heat sensitive layer is coated thereon or the organic amine derivative layer is provided between two heat sensitive layers, the melting point of the organic amine derivative should not necessarily be higher than that of the phenolic substance. Furthermore, even such organic amine derivatives as quaternary ammonium salts which decompose at higher than 200C and have no melting point or those which have a high melting point and do not melt with generally employable quantity of heat may be used in combination with a substance which melts upon heating to cause melting of the organic amine derivative. Moreover, the organic amine derivatives which are liquid at normal temperature may also be used in the same manner as the solid organic amine derivatives with use of an appropriate separating agent, namely, a substance which is insoluble in the organic amine derivative and is, upon heating, molten to cause fluidization of the organic amine derivative. However, those which are solid at normal temperature and have the melting point of 200C or less are generally preferred.

In the present invention according to which the organic amine derivative is used in combination with the normally colorless or palely colored chromogenic substance and the phenolic substance which causes coloration of said chromogenic substance upon heating, the mechanism of coloration and decoloration is considered as follows: when heat is applied to the heat sensitive layer, the phenolic substance is firstly molten and acts on the chromogenic substance to cause coloration and when heat is further applied and the temperature reaches a certain temperature, the organic amine derivative is molten and basic property of the organic amine derivative predominates over the effect of the phenolic substance to result in a basic atmosphere and to open lacton ring of the chromogenic substance to cause decolorization.

Instead of adding the organic amine derivative to the heat sensitive layer as explained above, the amine derivative layer may also be provided on or under the heat sensitive layer. In this case, the organic amine derivative is not required to be insoluble in solvent in preparation of a coating layer containing the organic amine derivative.

Amount of the organic amine derivative used may vary depending upon the conditions mentioned above, but may be within the range of 500 of the phenolic substance. When said amount is less than 10 the decolorization effect is insufficient and when more than 500 the decolorization effect is no longer so much increased.

The relative amounts of colorless or palely colored chromogenic substance, the phenolic substance and binder may vary in wide ranges, but generally the phenolic substance is in an amount of l 100 parts by weight, preferably 3 30 parts by weight per one part by weight of the chromogenic substance and the binder is in an amount of 5 50 parts by weight, preferably 40 parts by weight of the total solid matter in the heat sensitive coating liquid.

The organic amine derivatives used in the present invention may be classified into the following four groups:

1. Those represented by the general formula:

[wherein R R R R and R represent hydrogen, lower alkyl, cyclic alkyl, aryl which may contain substituent selected from a lower alkyl, alkoxy, nitro and- /or halogen, aralkyl, amino, alkylamino, acylamino, carbamoylamino, or benzimidazole group].

2. Those represented by the general formula:

[wherein R R R R and R have the same meanings as defined above and R represents lower alkylene,

phenylene or (wherein X is a lower alkylene, S, 0, S S0 or a single bond 3. Those represented by the general formula:

(wherein R R and R represent hydrogen, alkyl of 1 carbon atoms, amino substituted alkyl, cycloalkyl, aralkyl, aryl or heterocyclic ring residues and at least two of R R and R may bond to each other to form a ring including the N in said general formula). 4. Quaternary ammonium salts For easy understanding, these quaternary ammonium salts may be further classified into the following five groups having the following general formulas, but the present invention should not be limited to them. A.

RS-DII-R7 (wherein R R represent hydrogen, alkyl groups of l 20 carbon atoms, amino substituted alkyl groups, cycloalkyl groups, aralkyl groups, aryl group or heterocyclic residues, at least two of R R may bond to each other to form a ring including the N in said general for mula and X represents a counter anion).

v R4 4, +2 R5-N'- R1ON-R5' 2X" [wherein R, R and R R represent hydrogen, alkyl groups of l 20 carbon atoms, amino substituted alkyl groups, cycloalkyl groups, aralkyl groups, aryl group or heterocyclic residues, at least two of R, R and at least two of R R may bond to each other to form a ring including the N in said general formula or R and R may bond to each other to form a ring including the N in the general formula, R represents alkylene group of l 20 carbon atoms, xylylene group, allylene group, a single bond or (wherein A represents a single bond, alkylene, oxygen or sulfur) and X represents a counter anion].

(wherein R represents an alkyl group of l 20 carbon atoms or an aralkyl group, R represents hydrogen, an alkyl group, an aralkyl group or phenyl group, Y and Z represent elements necessary for formation of a heterocyclic ring together with N in the general formula, Y

represents carbon, Z represents carbon, oxygen, sulfur and/or nitrogen and X represents a counter anion). D.

i a Z N 'R N Z 2X [wherein R represents hydrogen, an alkyl group, an aralkyl group or phenyl group, R represents an alkylene group, an allylene group, xylylene group, a single bond or (wherein A represents a single bond; an alkylene group, oxygen or sulfur), Y and Z represent elements necessary for formation of a heterocyclic ring together with N in the formula, Y represents carbon, Z represents carbon, oxygen, sulfur and/or nitrogen and X represents a counter anion].

[wherein R represents an alkyl group of l 20 carbon atoms or an aralkyl group, R represents hydrogen, an alkyl group, an aralkyl group or phenyl group, R represents an alkylene group, an allylene group, a xylylene group, a single bond or (wherein A represents a single bond, an alkylene group, oxygen or sulfur), Y and Z represent elements necessary for formation of a heterocyclic ring together with N in the formula, Y represents carbon, Z represents carbon, oxygen, sulfur and/or nitrogen and X represents a counter anion].

The counter anions referred to above include halogens, naphthalenetrisulfonic acid, alkylbenzene sulfonic acids, benzenesulfonic acid, benzenesulfinic acid, alkyldiphenyletherdisulfonic acids, sulfamic acid, BF C B(C H PF etc.

Specific examples of the organic amine derivatives used in the present invention are enumerated below.

First, examples of quanidine derivatives are shown in Table 1 in which means cyclohexyl group.

i TABLE l-Cont inued TABLE l-Continued (33) @NH-C-NH These quanidine derivatives shown in Table 1 can easily be produced by the known methods or similar methods.

Next, specific examples of the quaternary ammonium salts and primary, secondary and tertiary amines are shown in the following Table 2, but the present invention is not limitative thereto.

TABLE 2 TABLE 2 Continued tallow-dimethylammonium l Br" I 01' 4% 4 9 [B(C6H3)4] I Br I 18 57 12 o s CH f 3 v 3 o H 1 (I; l 01 C1 C H 7 '5 i I 01' Cl l2 25 TABLE 2 Continued CN+ CH QCH N6 [CN- C H Q c21 N3 QW- CH2 0 o 0 CH 13 14 TABLE 2 -Continued TABLE 2 Continued QN CH2 CH2 CH N6 R fi i 0 N cH CH N 0 a 20104- H cH cH H "H I i H 3 3 HH QN (cH NO 2c1o v (H c i:*- CH N (c H 7 N N r v r 20 S0CH Y 3BF4 H c- N CH OCH N (C H5)3 (68) 2151 N /N I CH CH 4ClO H HH H lCHZ N NC (61) H N CH OCH 55 CH N 201' The organic amine derivatives shown in the above H HH Table 2 can easily be, produced by the known methods or the similar methods. 40 Two or more of these organic amine derivatives may v be used in combination to result in reduction of decol- ,HHHH 3 3 HHH orization temperature (reduction of melting point due 1 (52) to mixed meltin Thus, it becomes possible to adjust K H N CH 0 -N g I I g H2 the decolorization temperature.

" HH -H H Typical examples of the colorless or palely colored v 1 chromogenic substances used in the present invention are enumerated below, but the present invention is not limitative to these compounds only.

Crystal Violet lactone 5O Malachite Green lactone HH H 3,3-Bis( ara-dimeth lamino henyl)-6-amino htha- (65) L -K CH Q lide P y P p CH i Q /)v-l 2 3,3-Bis(p-dimethylaminophenyl)-6-(p-toluenesul- CH5 H HH H CH5 foamine)phthalide 5 5 3-Diethylamino-7-( N-methylanilino )fluoran 3 -Diethylamino-7-(N-methyl-p-toluidino)fluoran 6 4 3-Diethylamino-6-methoxyfluoran 3-Diethylamino7-chlorofiuoran 3-Diethylamino-6-methyl-7-chlorofluoran 3-Diethylamino-7-phenylfluoran N 2 2 N 3-Mo holino-5,6-benzofluoran P 3-Diethylamino-5-methyl-7-dibenzylaminofluoran 3-Diethylamino-7-dibenzylaminofluoran 6 3-Diethylamino-7,8-benzofluoran 5 3-Cyclohexylamino-6-chlorofluoran CH CH3 Benzo-B-naphthospiropyran I 24 The phenolic substances used in the present inven- 5 Lj 2@ 2 N N CH5 tion are those which are liquefied and/or gasified at E normal temperature, preferably at C or higher to react with said chromogenic substances to cause color- 15 ation of the chromogenic substances and these phenolic substances include carboxylic acids having phenolic hydroxyl group.

Typical examples of these phenolic substances are as follows:

4,4'-Isopropylidenediphenol 4,4'-Isopropylidenebis(2-chlorophenol) 4,4-Isopropylidenebis( Z-tert-butylphenol) 4,4'-sec-Butylidenediphenol 4,4'-( l-methyl-n-hexylidene)diphenol 4-Phenylphenol 4-Hydroxydiphenoxide Methyl-4-hydroxybenzoate Phenyl-4-hydroxybenzoate 4-I-Iydroxyacetophenone Gallic acid Phenyl gallate Salicylic acid anilide Salicylic acid Phenyl salicylate 2O 4,4-Cyclohexylidenediphenol 4,4-Cyc1ohexylidenebis( 2-methylphenol) 4,4'-Pentylidenediphenol 4,4-Thiobis( 6-tert-butyl-3-methylphenol) Novolak phenol resins Halogenated novolck phenol resins Among them, phenolic substances containing at least 2 hydroxyl groups in one molecule are especially preferred.

The heat sensitive recording material of the present invention can be summarily produced by the following method. That is, each of the phenolic substance, the chromogenic substance and the organic amine derivative is separately ground into the particles of less than several u and dispersed in a binder of an appropriate concentration by a grinder such as ball mill. Thus obtained three dispersions are mixed and to the mixture are optionally added a whiteness increasing agent, a wetting agent and other various fillers to obtain a heat sensitive coating liquid. The resultant coating liquid is coated on an appropriate support and is dried. As a binder, generally known water soluble binders such as polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, gum arabic, casein, gelatin, styrene-maleic anhydride copolymer, starch, polyacrylates, styrene-butadiene latex emulsion, etc. and petroleum resins such as terpene resin, cyclic rubber, etc. may be used.

Moreover, the organic amine derivative may also be added to an upper layer on the heat sensitive layer or an under layer below the heat sensitive layer to obtain same result.

As the support, paper is ordinarily used, but synthetic resin films, laminate paper and woven fabric sheets may also be used. I

In the present invention, the organic amine derivative may be contained in the heat sensitive layer, on the upper or under layer of the heat sensitive layer to attain decolorization effect, but when the organic amine derivative is contained in a layer other than the heat sensitive layer, preferably those which have relatively higher decolorization effect than those to be used in the heat sensitive layer should be used. In case of using those of lower decolorization effect, decolorization is not completed and some color is formed.

When said phenomenon is utilized in dichromatic color formation, e.g., by using two heat sensitive layers and the organic amine derivative having relatively low decolorization effect is contained in either one of said two heat sensitive layers, the heat sensitive layer containing the organic amine derivative is, of course, decolorized at a temperature higher than a certain temperature, but the adjacent heat sensitive layer is not completely decolorized and some color is formed. Thus, dichromatically developed color images of single colors are obtained.

In the above case, if an organic amine derivative having a high decolorization effect is employed in place of that of low decolorization effect, not only the heat sensitive layer containing the organic amine derivative, but also the adjacent heat sensitive layer is decolorized at a temperature higher than a certain temperature. In such case, therefore, e.g. an intermediate layer can be provided between the two heat sensitive layers to prevent the diffusion of the organic amine derivative molten by heat printing. Alternatively, instead of providing the intermediate layer, complete decolorization may also be prevented by increasing the amount of the heat sensitive composition in the adjacent layer than the usually employed amount.

The following examples are included for a further understanding of the invention.

Preparation of heat sensitive coating liquid (Liquid A) Liquid (a) Crystal Violet lactone l g 20 Aqueous solution of polyvinyl alcohol 5 g Water 15g Liquid (b) 4,4-( l-Methyl-n-hexylidene) diphenol 5 g 20 Aqueous solution of polyvinyl alcohol 25 g Water g Liquid (c) The compound (1) in the Table l 8 g 20 Aqueous solution of polyvinyl alcohol 40 g Water 120 g Each of said liquids (a), (b) and (0) were separately ball-milled for 2 days and weremixed. To the mixture were added 20 g of 50 wheat starch dispersion, 5 g of 20 wax emulsion (Trade name Repol No. 50 produced by Daikyo Chemical K.K.) and 1 cc of surfactant Dowfax 2A-l (produced by Dow Chemical Co.) to obtain heat sensitive coating liquid A.

Preparation of heat sensitive coating liquid (Liquid B) Coating liquid B was prepared in the same manner as of the preparation of the Liquid A except that 3-diethylamino-7-chlorofulorane was substituted for Crystal Violet lactone in liquid (a), 4,4-isopropylidenediphenol was substituted for 4,4'-(1-methyl-n-hexylidene)diphenol in liquid (b) and compound (2) in Table l was substituted for compound l in Table l in liquid (c).

Example 1 Liquid A prepared as mentioned above was coated on an ordinary paper having a basis weight of 50 g/m in a dried coating weight of 8 g/m and the coated film was dried to obtain a heat sensitive paper.

This heat sensitive recording paper formed blue color at C C, but formed no color at higher than 120C.

Heat sensitive recording papers were also produced in the same manner as mentioned above except that liquid (c) of the Liquid B to which 0.5 cc of Dowfax 2A-1 was added was coated upon said first layer in a dried coating weight of 2 g/m and dried to obtain a heat sensitive recording paper exhibiting nearly the I same properties as of Example 4.

Example 6 The liquid (a) of the Liquid A and the liquid (b) of Table 3 Range of color Temperature at Guanidine forming temwhich no color Note derivative perature was formed Not the None Higher than 90C None present invention The Table l (1) 90 120C Higher than 120C present invention Table l (2) 90 130C Higher than 130C Table l (11) 90 120C Higher than 120C Table l (14) 90 130C Higher than 130C Table l (29) 90 120C Higher than 120C 7 Table 1 (30) 90- 110C Higher than 110C Table 1 (31) 90 120C Higher than 120C Table l (32) 90 120C Higher than 120C Example 2 Only the liquid (c) in said Liquid A was coated on an ordinary paper having a basis weight of 50 g/m in a dried weight of 2 g/m and was dried. Then, a mixed liquid of liquids (a) and (b) to which 0.5 cc of Dowfax 2A-l was added was coated upon the first layer in a dried coating weight of 3 g/m and was dried to obtain a heat sensitive recording paper. This heat sensitive recording paper formed blue color at 90 120C and formed no color at higher than 120C. Example 3 Liquid (a) in said Liquid A where Crystal Violet lactone was replaced with 3-diethylamino-6-methyl-7- chlorofluorane and the liquid (b) in Liquid A where 4,4-(1-methyl-n-hexylidene)diphenol was replaced with 4,4'-isopropylidenediphenol were separately ballmilled for 2 days and then the two liquids were mixed. To the mixture was added 0.6 g of Epiol E-l (Trade name of a hardener manufactured by Nihon Yushi K.K.) and they were mixed to obtain a heat sensitive coating liquid. This heat sensitive coating liquid was coated on an ordinary paper having a basis weight of 50 g/m in a dried coating weight of 3 g/m and was dried and then said Liquid A was coated upon the first layer in a dried coating amount of 8 g/m and dried to obtain a heat sensitive recording paper. This heat sensitive recording paper formed blue color at 90 120C and formed red color at higher than 130C. Substantially no blue color was incorporated into said red color. Thus distinct two colors were obtained. Example 4 A heat sensitive recording paper was produced in the same manner as Example 1 with the exception that Liquid A was replaced with Liquid B. Thus obtained heat sensitive recording paper formed red color at 140 170C, but formed no color at higher than 170C. Example A mixed liquid of liquids (a) and (b) of the Liquid B was coated on an ordinary paper having a basis weight of 50 g/m in a dried coating weight of 3 g/m Then,

the Liquid A where 4,4'-( l-methyl-n-hexylidene)diphenol was replaced with 4,4'-cyclohexylidene-bis(2- methylphenol) were mixed and to the mixture was further added 0.6 g of Epiol E-l00 to obtain a heat sensitive coating liquid. This heat sensitive coating liquid was coated on an ordinary paper having a basis weight of 50 g/m in a dried coating weight of 5 g/m and dried. Then, the Liquid B was coated upon said first layer in a dried coating weight of 6 g/m and dried to obtain a heat sensitive recording paper. This heat sensitive recording paper formed red color at C and blue color at higher than C. Substantially no red color was incorporated into the blue color and thus distinct two colors were obtained. Example 7 The dried coating weight of the first heat sensitive layer in the above Example 6 was changed to 3 g/m and thereupon was coated an aqueous solution of polyvinyl alcohol containing a surfactant in a dried coating weight of 1 g/m as an intermediate layer and dried. Then, the second heat sensitive layer in the Example 6 was further coated thereupon in a dried coating weight of 8 g/m and was dried to obtain a heat sensitive recording paper, which exhibited nearly the same results as in Example 6. Example 8 Liquid (d).

Compound (1 1) in Table 1 Compound (9) in Table 2 10 Aqueous solution of casein Water one goon 0c once 99 'JIUI moo The liquids (c) and (b) in Example 1 were added to said liquids (d) and (e) to obtain a heat sensitive coating liquid, which was coated on an ordinary paper hav- Liquid (f) Compound (2) in Table 2 l Aqueous solution of casein Water Liquid (g) Crystal Violet lactone Aqueous solution of polyvinyl alcohol Water Liquid (h) 4,4-( 1-methyl-n-hexylidene)- diphenol 5 Aqueous solution of polyvinyl alcohol 8 g Water The above Liquids (f), (g) and (h) were separately ball-milled for 2 days. The Liquid (f) was coated on an ordinary paper having a basis weight of 50 g/m in a dried coating amount of 3 g/m and dried. A heat sensitive coating liquid obtained by mixing said Liquids (g) and (h), 18 g of aqueous solution of polyvinyl a1- cohol and 1 cc of 10 Dowfax 2A-1 was coated upon the first layer of the Liquid (f) in a dried coating weight of 3 g/m and dried to obtain a heat sensitive recording paper. This recording paper formed blue color at 90 1 10C and formed no color at higher than 110C. Example 10 Heat sensitive recording papers were produced in the same manner as in Example 9 with the exception that the compounds enumerated in Table 4 were used in place of compound (2) in Table 2. In this case, when the compounds enumerated in Table 4 were water soluble, they were not required to be ball-milled. The results obtained from these recording papers are shown in Table 4. As is clear from Table 4, the recording papers containing the organic amine derivatives of the present invention were more excellent in decolorizing effect than those containing alcoholic decolorizing agents.

Table 4 Range of tem- Temp. at Degree Decolorizing perature at which no of deagent which color color was colori- Note was formed formed zation Not the None Higher than None X present 90C invention Higher Polyethylene 90 1 10C than A oxide 120C 2,4,6-Octa triene-l-ol The Compound (4) 0 present in Table 2 invention Compound (9) O in Table 2 Compound (23) O in Table 2 Compound (33) T O in Table 2 Compound (44) O in Table 2 Table 4-continued Range of tem- Temp at Degree Decolorizing perature at which no of deagent which color color was colori- Note was formed formed zation Compound (56) O in Table 2 Compound (2) in Table 1 and Higher Compound (4) 9O C than 0 in Table 2 l 10C In combination (1 l) The marks which indicate the degree of decolorization mean as follows:

1. O means that the recording paper was decolorized to practically utilizable degree.

2. A" means that the recording paper was decolorizcd, but the degree was such as not practically utilizable 3. X" means that the recording paper was not decolorized.

Example 1 1 Liquid (i) Compound (57) in Table 2 2 g Annowax (Trade name for methylenebisstearamide manufactured by Lion Annour C0 1 g 10 Aqueous solution of casein 6 g Water 30 g The above Liquid (i) was ball-milled for 2 days and coated on an ordinary paper having a basis weight of 50 g/m in a dried coating weight of 5 g/m and was dried. A mixed liquid of 18 g of 10 aqueous solution of polyvinyl alcohol, 10 Dowfax 2A-l and Liquids (g) and (h) where 4,4'-isopropylidenediphenol was substituted for 4,4'-( l-methyl-n-hexylidene)diphenol in Example 9 was coated upon the first layer in a dried coating weight of about 3 g/m and was dried to obtain a heat sensitive recording paper. The compound (57) in Table 2 was a substance which decomposes at higher than 260C, but since it was a heat meltable substance, it exhibited decolirizing effect at about 180C. Therefore, said heat sensitive recording paper formed blue color at 50 C and was decolorized at C.

Example 12 Liquid (j) 3-Diethylamino-7-chlorofluorane l g 5 Aqueous solution of hydroxyethyl cellulose 5 g Water 44 g Liquid (k) 4,4'-( LMethyl-n-hexylidene} diphenol 6 g 5 Aqueous solution of hydroxyethyl cellulose 30 g Water 26.4 g Liquid (1) Compound (10) in Table 2 10 g 5 Aqueous solution of hydroxyethyl cellulose 50 g Water 44 g The above liquids (j), (k) and (l) were separately ball-milled for 2 days and then they were mixed to obtain a heat sensitive coating liquid, which was coated on an ordinary paper having a basis weight of 50 g/m .in a dried coating weight of about 5 g/m and dried to obtain a heat sensitive recording paper. This recording paper formed red color at 90 1 10C and was decolorized at higher than 120C.

21 Example 13 A mixed dispersion of ferric stearate, gallic acid and titanium oxide was prepared in petroleum with use of a suitable binder such as Piccolite. The resultant dispersion was coated on an ordinary paper having a basis weight of 50 glm Thereupon was coated ball-milled Liquid (m) in a dried coating weight of about 3 glm A mixture of ball-milled Liquids (n) and was coated upon said layer of Liquid (m) in a dried coating weight of 3 g/m and dried to obtain a heat sensitive recording paper. This recording paper formed red color at 110 130C and this red color completely disappeared at higher than 130C and black color was formed in the under layer.

Example 14 Liquid (p) Compound (8) in Table 2 l0 Aqueous solution of casein Water fluorescein Water Liquid (1') Crystal Violet lactone Water Liquid (p) Liquid (5) 4,4'-( l-Methyl-n-hexylidene diphenol 5 Aqueous solution of Celogen 7-A (Trade name for carboxymethylcellulose manufactured by Daiichi Kogyo Seiyaku K.K.

Water Liquids (p), (q), (r) and (s) were separately ballmilled for l 2 days. Then, Liquid (p) was coated on an ordinary paper having a basis weight of 50 g/m in a dried coating weight of 3 g/m and dried. Liquids (q), (r) and (s) were mixed and 30 g of 10 Celogen 7-A, 2 cc of 10 Dowfax and 1.5 g of 20 Repol No. 50 (Trade name forwax emulsion manufactured by Daikyo Kagaku K.K.) was further added thereto. The resultant mixture was coated upon said first layer. The resultant heat sensitive recording paper formed blue color at 90 120C and red color at higher than 130C. Example Example 3 was repeated except that the all coating liquids were coated as one layer on the ordinary paper to obtain the same results as those in Example 3. That is, the following liquids were separately ball-milled and dispersed for 2 days and then these dispersions were mixed. To the resultant mixture was added 0.5 cc of Dowfax 2A-1 and the liquid obtained was coated on the ordinary paper in a dried coating weight of 3 g/m and dried.

Crystal Violet lactone 20 Aqueous solution of polyvinyl alcohol Water 4,4-(1-Methyl normal hexylidene)diphenol 20 Aqueous solution of polyvinyl alcohol Water 3-Diethylamino-6-methyl-7- chlorofluorane 20 Aqueous solution of polyvinyl alcohol Water 4,4-lsopropylidenediphenol 20 Aqueous solution of polyvinyl alcohol Water Compound (I) in Table l 20 Aqueous solution of polyvinyl alcohol Water M LIIUI (It 09W 0005M (H0909 0Q 0905 00 009 W Example l6 Example 6 was repeated except that the liquid (c) in Liquid B was provided as an intermediate layer, namely, the upper and lower heat sensitive layers contained no organic amine derivative. The obtained heat sensitive recording paper exhibited nearly the same results as in Example 6.

What is claimed is:

1. In a heat sensitive recording material comprising a support having a heat sensitive layer or layers thereon which comprises colorless or light colored chromogenic substance and phenolic substance capable, upon heating, of causing color formation of said chromogenic substance, wherein at least one organic amine derivative in the amount of at least 10% by weight of the phenolic substance is contained as a decolorizing agent in said heat sensitive layer or another layer adjacent to said heat sensitive layer.

2. A heat sensitive recording material according to claim 1, wherein said organic amine derivative is contained in an amount of 10 500 by weight of the phenolic substance.

3. A heat sensitive recording material according to claim 1, wherein said recording material has only one heat sensitive layer containing two kinds of the chromogenic substances and the phenolic substances, respectively and the organic amine derivative.

4. A heat sensitive recording material according to claim 1, wherein the adjacent layer is an intermediate layer containing the decolorizing agent.

5. A heat sensitive recording material according to claim 1, wherein said recording material comprises two heat sensitive layers, one of which contains the organic amine derivative.

6. A heat sensitive recording material according to claim 1 wherein said organic amine derivative is a guanidine derivative of the formula:

wherein R R R and R represent hydrogen, lower alkyl, cyclic alkyl, aryl, aryl substituted with lower alkyl, alkoxy, nitro or halogen, aralkyl, amino, alkylamino, acylamino, carbamoylamino, or benzimidazole, and R represents hydrogen, lower alkyl, cyclic alkyl, aryl, aryl substituted with lower alkyl, alkoxy, nitro or halogen, aralkyl, amino, alkylamino, acylamino, carbamoylamino, benzimidazole or in which R represents lower alkylene, phenylene or claim 6 wherein said guanidine is contained in an amount of lO500% by weight of the phenolic substance.

10. A heat sensitive recording material according to claim 9 which forms color at a temperature of at least C. 

1. IN A HEAT SENSITIVE RECORDING MATERIAL COMPRISING A SUPPORT HAVING A HEAT SENSITIVE LAYER OR LAYERS THEREON WHICH COMPRISES COLORLESS OR LIGHT COLORED CHROMOGENIC SUBSTANCE AND PHENOLIC SUBSTANCE CAPABLE, UPON HEATING, OF CAUSING COLOR FORMATION OF SAID CHROMOGENIC SUBSTANCE, WHEREIN AT LEAST ONE ORGANI AMINE DERIVATIVE IN THE AMOUNT OF AT LEAST 10% BY WEIGHT OF THE PHENOLIC SUBSTANCE IS CONTAINED AS A DECOLORIZING AGENT IN SAID HEAT SENSITIVE LAYER OR ANOTHER LAYER ADJACENT TO SAID HEAT SENSITIVE LAYER.
 2. A heat sensitive recording material according to claim 1, wherein said organic amine derivative is contained in an amount of 10 - 500 % by weight of the phenolic substance.
 3. A heat sensitive recording material according to claim 1, wherein said recording material has only one heat sensitive layer containing two kinds of the chromogenic substances and the phenolic substances, respectively and the organic amine derivative.
 4. A heat sensitive recording material according to claim 1, wherein the adjacent layer is an intermediate layer containing the decolorizing agent.
 5. A heat sensitive recording material according to claim 1, wherein said recording material comprises two heat sensitive layers, one of which contains the organic amine derivative.
 6. A heat sensitive recording material according to claim 1 wherein said organic amine derivative is a guanidine derivative of the formula:
 7. A heat sensitive recording material according to claim 6 wherein R5 is hydrogen, lower alkyl, cyclic alkyl, aryl, aryl substituted with lower alkyl, alkoxy, nitro, or halogen aralkyl, amino, alkylamino, acylamino, carbamoylamino or benzimidazole.
 8. A heat sensitive recording material according to claim 7, wherein said guanidine derivative contains at least 2 cyclohexyl groups.
 9. A heat sensitive recording material according to claim 6 wherein said guanidine is contained in an amount of 10-500% by weight of the phenolic substance.
 10. A heat sensitive recording material according to claim 9 which forms color at a temperature of at least 90*C. 